Reliability in Large-Capacity Bandwidth-Limited Storage Systems

As time goes by, storage systems are required to reliably store increasing amounts of data. Some earlier solutions, designed for relatively small systems, are reaching their limit. The problem of storage reliability is aggravated by ongoing tendencies of (networked) storage systems, e.g., the growth gap between the capacity of each device and its bandwidth, and the advent of mass-produced cheap devices of decreasing reliability.
In this work we study bounds and solutions for very large systems of high capacity devices. Using simple information-theoretic bounds, we show the eventual necessity of a scalable hierarchical system. We next describe and analyze such a system. The salient points of our system are protection of data by their estimated access-intensity, unequal error-protection by data importance, assumption of a lenient and realistic disk-replacement policy, and competitive transition of data between different levels by predicted access-intensity.

By: Ami Tavory, Valdimir Dreizin, Shmuel Gal, Meir Feder

Published in: H-0211 in 2003


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